Diguise, Containment and the \u3cem\u3ePorgy and Bess\u3c/em\u3e Revival of 1952–1956

Life in the cultural shallows tested the character of American art. Where the Depression had encouraged artists to engage in social and political criticism, the early cold war years constricted and confounded them. By conflating dissent and disloyalty, the triumphant conservatism of the cold war not only shifted the frame of cultural reference dramatically to the right, it narrowed it as well. This had a profound impact on America’s cultural establishment. With conservatives now in possession of the moral absolutes, the more politically progressive artists felt pressed into the position of endorsing ambivalence and moderation. The result, for many, was a quiet retreat from principle; unwilling to blindly adopt the conservatives’ standard of good and evil, and yet unable to risk their own, forward-thinking artists ended up chronicling rather than challenging their age. So much of fifties art became an exploration of the ordinary—domestic comedy, social commentary, “wistful melodrama,” sermons on rootlessness or delinquency or affluence—instead of a questioning of the larger truths. Tragedy, which, by challenging certitudes, required the moral commitment of liberal writers, became, in this context, anachronistic. “We are not producing real tragedy,” observed Leonard Bernstein in 1952, because “caution prevents it, all the fears prevent it; and we are left, at the moment, with an art that is rather whiling away the time until the world gets better or blows up.” Art had adopted the Technicolor blandness of the age

Groups of piecewise projective homeomorphisms

The group of piecewise projective homeomorphisms of the line provides straightforward counter-examples to the so-called von Neumann conjecture. The examples are so simple that many additional properties can be established.Comment: This version submitted to PNAS on October 22, 2012. Final version published in PNAS at http://dx.doi.org/10.1073/pnas.121842611

A note on topological amenability

We point out a simple characterisation of topological amenability in terms of bounded cohomology, following Johnson's reformulation of amenability

French theories in IS : an exploratory study on ICIS, AMCIS and MISQ.

French theories; Information Systems Research; Actor-network theory;

The norm of the Euler class

We prove that the norm of the Euler class E for flat vector bundles is $2^{-n}$ (in even dimension $n$, since it vanishes in odd dimension). This shows that the Sullivan--Smillie bound considered by Gromov and Ivanov--Turaev is sharp. We construct a new cocycle representing E and taking only the two values $\pm 2^{-n}$; a null-set obstruction prevents any cocycle from existing on the projective space. We establish the uniqueness of an antisymmetric representative for E in bounded cohomology.Comment: 19 page

Non-unitarisable representations and random forests

We establish a connection between Dixmier's unitarisability problem and the expected degree of random forests on a group. As a consequence, a residually finite group is non-unitarisable if its first L2-Betti number is non-zero or if it is finitely generated with non-trivial cost. Our criterion also applies to torsion groups constructed by D. Osin, thus providing the first examples of non-unitarisable groups not containing a non-Abelian free subgroup

Strong law of large numbers with concave moments

In this note not intended for publication, it is observed that a wellnigh trivial application of the ergodic theorem of Karlsson-Ledrappier yields a strong LLN for arbitrary concave moments.Comment: Not for publication. (2 pages